1. Field of Invention
This invention relates to a drive arrangement for a motor vehicle door or hatch which can be moved by a motor with a planet gear and a brake device with a brake, the planet gear having a drive shaft, a driven shaft, a sun wheel, a planet carrier with planet wheels and a ring gear, the drive shaft being able to be driven by the motor and the driven shaft being coupled to the motor vehicle door or hatch. One of the elements which include the sun wheel, planet carrier and ring gear being coupled to the drive shaft, a second of the elements which include the sun wheel, planet carrier and ring gear being coupled to the driven shaft and the third of the elements which include the sun wheel, planet carrier and ring gear being able to be braked or blocked by means of the brake. The third of the elements which include the sun wheel, planet carrier and ring gear is not braked or blocked in the first position of the brake—released position—and in this position, the motor vehicle door or hatch is movable by hand, unhindered by the drive arrangement and the third of the elements which include the sun wheel, planet carrier and ring gear being braked or blocked in the second position of the brake—braking position—and thus, the drive shaft is coupled to the driven shaft so that, in this position, the motor vehicle door or hatch is able to be moved by a motor. The brake device has a brake drive which is separate from the drive which drives the drive shaft and the brake being able to be moved at least from one of the two positions into the other of the two positions by means of the brake drive.
The expression “motor vehicle door” should be understood here to be not only the side door of a motor vehicle, but also a sliding door or the like of a motor vehicle. The term “motor vehicle hatch” is defined as a rear hatch, trunk lid, optionally also the hood, etc.
2. Description of Related Art
The prior art discloses a motor vehicle lock (DE 199 35 589 A1) in which a planet gear is used as the gearing for driving an actuating lever which is coupled to a ratchet. The planet gear in this respect is part of an opening aid. The planet gear is made such that the actuating lever can be driven by two different actuating elements, specifically a normal actuating element and an emergency actuating element. The different actuating elements are used for force transmission which is matched to the respective purpose. The planet gear enables the respective actuation by the drive to be operated with a direction of rotation which differs in each case. The planet gear yields a compact construction.
Furthermore, the prior art discloses a drive device (International Application publication WO 00/36259 A1 which corresponds to U.S. Pat. No. 6,142,551) which is used to actuate a motor vehicle hatch by motor, therefore to open and close it. To do this, on each side of the motor vehicle hatch there is a respective motor with a gearing assigned to the motor, with which the motor vehicle hatch can be actuated. In order to also enable manual actuation of the motor vehicle hatch, the motor and gearing are made such that the motor is not blocked, but concomitantly turned when the motor vehicle hatch is manually actuated.
Conversely, another known drive device (published German Patent Application DE 40 41 480 A1) allows manual and motorized actuation of functional parts, especially of a motor vehicle door or hatch, without the motor being concomitantly moved when the motor vehicle door or hatch is manually actuated. There is a planet gear with a ring gear that can be driven by a motor. The driven shaft of the planet gear which is coupled to the motor vehicle door or hatch is rigidly coupled to the planet carrier. Moreover, there is a brake device which blocks the sun wheel during the motorized actuation of the ring gear so that the motion of the ring gear is transferred to the planet wheels, and thus, to the planet carrier so that, ultimately, the motor vehicle door or hatch is actuated.
For manual actuation of the motor vehicle door or hatch the sun wheel is driven by means of a crank arm. The ring gear is blocked in doing so by the coupling to the motorized drive which is designed to be self-locking, so that the torque of the sun wheel is transferred to the planet carrier, and thus, to the driven shaft. If, with the drive motor stationary, the motor vehicle door or hatch itself is moved by hand, this motion is also possible because, then, the crank arm is simply entrained as it turns backwards.
The brake device is actuated in the above described drive device by the same drive which also drives the ring gear. For this reason, rapid decoupling between the drive shaft and the driven shaft in an emergency, for example, when a hand is pinched in a sliding door, is not possible. First of all, the drive must be brought completely to rest before the action of the force on the drive shaft is stopped and manual or motorized actuation of the functional part in the opposite direction is possible. Moreover, the braking action in this configuration of the drive device is not optimum.
Another known drive device (German Patent Application DE 101 17 934 A1 and corresponding to U.S. Patent Application Publication 2004/0097318 A1), upon which the present invention is based, is used for motorized actuation of the rear hatch of a motor vehicle. The drive device has a motor and a planet gear which is assigned to the motor. The driven shaft of the planet gear is coupled to the rear hatch. In order to be able to ensure easy manual actuation in addition to motorized actuation, the planet gear is also used here as a clutch. For this reason, there is a brake device which allows braking of the ring gear for motorized actuation and which allows release of the ring gear for manual actuation. The brake device has a brake and a brake drive, the brake being adjustable by means of the brake drive between a braking position and a released position. To move the brake into the braking position, the brake is moved towards the ring gear until it engages the ring gear, positively or nonpositively, and accordingly, brakes or blocks it.
The disadvantage in the known braking arrangement with the described braking concept is the fact that the braking action can only be ensured especially for heavy rear hatches when the brake drive is made accordingly strong. This leads to high demands for installation space and to high costs.
It should be pointed out that there are also similar drive arrangements for use in sliding doors (U.S. Pat. Nos. 6,125,586 and 6,460,295). In these drive arrangements, there is a braking device which allows braking of the sun wheel to implement the clutch action.